Traffic control system



J. L. BIACH ET AL TRAFFIC CONTROL SYSTEM Filed April 23, 1930 May 7, 1940. 2.199.571

5 Sheets-Sheet 1 INVEN TOR.

M, My :5: ATTORNEYS.

May 7, 1940.

J. L. BIACH. ET AL.

TRAFFIC common SYSTEM Filcd April '23, 1930 5 Sheets-Sheet 72 WIRES ISIIA'Z AT PELAYQ so I l INVENTOR.

Di. aw,

1 ATTORNEYS.

INVENTOR 5 Sheets-Sheet 3 J. L. BIACH Er AL Tmmmc. CONTROL SYSTEM Filed April 23, 1930 May 7, 1940.-

J. L. BIACH ET. AL

TRAFFIC CONTROL SYSTEM Fii d mm 23, 1930 I May 7; 1940,

5 Sheets-Shet 4 INVENTOR y 1940- J. L. BIACH mm. 2.199.571

TRAFFIC COMBQL SYSTEM Filed A ril 23 @950 s Sheets-Sheet 5 INVENTOR JOHN L. D/AcH Alva l-hmey A. 1444 cox (20M bf (51% W ATTORN EY Patented May 7, 1940 UNITED STATES PAT IE 7 2,199,571 raarrrc coN'raor. SYSTEM Application April 23, 1930, Serial No. 446,480

so Claims. (Cl. 177-337) This invention relates to a traihc system capable of use in numerous different associations but primarily intended for employment with vehicle lanes such as roadways, and particularly at points of intersection of roadways, the present invention aiming to provide an automatic system by means of which traiiic will be expeditiously handled and which system to the greatest extent if not completely will be controlled in its iunctionings by the presence of traflic along the vehicle lanes.

Subject matter relating to the "periodic call feature disclosed in the present application is claimed in application Serial No. 73,156 flied April '7, 1936, by Charles D. Geer as a division of the present application. Such subject matter is not claimed in the present application.

Subject matter relating to the "speed proportional control" feature disclosed in the present application is claimed in application Serial No. 446,479 filed April 23, 1930, by Frederick G. Kelly, Jr., and no claims are made in the present application to such subject matter.

It is an object of the invention to provide an arrangement of apparatus furnishing a system of this character and by means of which traflic will be handled with maximum expediency and minimum delay periods and in which moreover the system will embrace a factor of safety such that the danger of accidents between vehicles or between vehiclesand pedestrians will be reduced to a minimum, if not entirely eliminated.

A further object is that of providing a system of this character, the several units of which will be individually simple and rugged in construction and embrace relatively few parts. these units when assembled providing a system operating over long periods of time with freedom from mechanical and/or electrical diiliculties. Moreover, these units to the greatest extent will be capable of individual adjustment so that while at the time of their manufacture, conditions may generally be approximated, adjustments may be made at the time of or subsequent to their installation at an actual traific intersection so as to take into account the characteristics individual to the traffic flow along the vehicle lanes comprising such intersection.

. A still further object is that oi providing a traitlc control system in which in the functlonings oi the systems, account may be taken of the amount of waiting traffic as well as the amount of moving trafflc, so that on the one hand undue delays will not be incurred and on the other hand, the danger of a relatively slow moving .The right or way device, to inform the traflic in vehicle becoming trapped at the intersection will be reduced to a minimum.

Still another object is that of construction of a system, the several units of which will function in the event of one condition of trafllc to sub- 31 stantially instantaneously transfer the right of way from one vehicle lane to the intersecting vehicle lane upon the approach of a vehicle along the latter, but in the event of vehicles passing along the first vehicle lane and approaching the 10 intersection will delay this transfer of right of way for a period adequate to assure safety of transfer.

With these and further objects in mind, reierencc is had to the attached sheets of drawings 15' illustrating one practical embodiment of the invention and in which:

Figure 1 is a diagrammatic view showing a highway intersection employing a signal system embodying our invention;

Fig. 2 is a detailed view showing a section of a vehicle actuated control device;

Figs. 3 and 4 show diagrammatic representations of timing mechanisms;

- Figs. 5 and 6 together comprise diagrammatic ,views showing the circuits of an apparatus for operating the signal at intersecting trafllc lanes.

Fig. '7 shows an enlarged and'more detailed view of the ratcheting mechanism employing the rack I85 in Fig. 5 for example.

A self regulating automatic traflic control system embodying our invention may comprise three'parts: a vehicle actuated control, trafllc responsive device or detector placed in or at the side of a road or vehicle lane. an electrical time limiting control system, and a signal de-- vice to indicate right of way to trafllc. A function of the vehicle actuated control device is such that vehicles approaching on the several traflic lanes actuate various electrical control circuits. These actuations control the operation of the electrical time limitation control system, which in turn controls the right of way device.

each street when to go and when to stop, may be the standard red, yellow and green lights now in general use, but may also be any other convenient or desirable form. The vehicle actuated control maybe 0! several types as hereinafter mentioned:

One means actuated'by the approaching vehicle may be of a mechanical nature such as a mechanical switch located in or at the side of the street, an electrical contact being made upon passage or the vehicle. n

Another means for detecting and recording the presence of an approaching vehicle may be a beam of light proiectedacross the highway and received upon a photo-electric or light sensitive electrical cell, so that an approaching vehicle causes an interruption or fluctuation in an electrical current passing through the photo-electric or light sensitive cell.

An electrical magnetic device located in the street or at the side of the street may also be arranged in such a manner that an approaching vehicle shall actuate the device to control an electric circuit.

Obviously, any other form of vehicle indicator could be used.

The time limit control circuit operates as follows: Assume that there are no vehicles approaching on the intersecting streets, designated for example, by A and B. Then the right of way will be -indicated to the street which last required it; for

example, A Street. A vehicle approaching from B Street now operates the B Street actuating means, and the control mechanism, ai'ter showing a suitable warning signal, transfers right of way to B Street. B Street now has the right of way and vehicles approaching on it may cross the intersection. The right of way will be transferred back to A Street under any one of the following conditions: I

Condition I.--Ii' a vehicle approaches on A Street and all B Street trafllc has passed the in tersection.

Condition IL-H a vehicle approaches on A Street and B Street tramcis still moving at the end of a predetermined period (such as seconds), the right of way is transferred to A Street.

Condition III.Ii no vehicles approach on A Street, then, whether or not trailic is moving on B Street, right 01 way will be called to A Street and will be yielded to A Street as under Conditions I and II above.

The various periods are controlled by suitable timing mechanisms.

Provision to transfer the right 01 way to A Street as outlined under Condition I above is accomplished through the use of a timing mechanism which provides sumcient time for the individual B Street vehiclesdzo cross the intersection. This timing mechanism is reset toward its starting position each time a vehicle operates the B Street actuating means. Hence, it no further vehicles approach on B Street, this timing mechanism will eventually completetiming theperiod it is set for: and when such time is reached, the right of way is transferred to A Street. The action is of course similar when the right of way is transferred from A Street to B Street.

To provide for Condition II mentioned above, in which continuous B Street traffic must be interrupted, another timing mechanism is provided whichis not reset by vehicles on B Street;. and which starts timing when the vehicle approached on A Street. When it has timed the period it is set for, the right of way is transferred to A Street.

To provide for Condition III mentioned above, we provide another timing mechanism which starts timing B Street right 01' way as soon as right of way appears on B Street. When it has timed the period it is set for, it calls the right of way to A Street, similar to the way in which right of way would be called to A Street by a vehicle approaching on A Street and thus simulates the eilect oi actuation oi the: vehicle actuated control on A Street by such a vehicle. Aiter right of way has been called in this manner, it will be transferred as outlined in either Condition I or Condition II, depending upon conditions in B Street.

When right of way is transferred as in Condition II, vehicles are on B Streetwhich have not had suflicient time to cross the'intersection, even though they have actuated the B Street actuating means. The control system is left in such a condition that as soon as A Street trafllc permits, right of way will be transferred to B Street without requiring any additional actuation oi the B Street vehicle actuated means.

The timing mechanism which is reset by traiflc, is so arranged that it may be reset in accord with the speed oi. the vehicle causing the resetting. And thus the time or protection period given each vehicle is commensurate with the speed of the vehicle. In this manner, no vehicle receives an unnecessarily long protection period; thus avoiding needless delay in the interfer-ing lane. i

The chief function of the warning signal when a stop signal is changing to right of way, is to indicate to waiting vehicles that such change is about to occur, and to get ready to proceed. But, when the change is from right of way to stop,

it indicates to moving vehicles that they are about to lose right of way, and accordingly the vehicles must be brought to a stop. The warning signal thus acts as a very important safeguard.

Whenever right of way is transferred as outlined in Condition I, all traflic has ceased on the lane which is losing right of way. Thus, there are no vehicles about to lose right of way, and consequently the warning signal may be quite short. But when right of way is transferred, as outlined in Condition II, some vehicles are about to lose right of way, and accordingly a longer warning signal should be given. This is accomplished by providing a mechanism which times the warning signal in a different way, depending whether the right of way is transferred as outlined in Condition I, or whether it is transferred as outlined in Condition II.

1' several vehicles have passed the actuating means while being given the stop signal, some time will elapse, after they have been given the right of way signal, before the last of said vehicles gets into motion. This time may be quite considerable. and may exceed the protection period provided by the resettable timing'mechanism. We thus provide an additional timing mechanism, the time period 01' which is proportional to the number of vehicles that have passed the actuating means. but are not allowed to proceed. This timing mechanism begins to time as soon as right of way appears on its street: and only after it has finished timing its period, may the resettable timer begin to operate.

While there has been described above a self regulating automatic 'trafllc control system embodying this invention, and there has been shown that this invention may comprise three inter- 2,199,571 ferred, visual, and is indicated at 5. It embraces red and green electric lamp reflectors or lenses visible from either direction on A Street, but not visible on B Street; red and green electric lamp reflectors, or lenses, visible from either direction on B Street, but not visible on A Street; and preferably a yellow electric lamp lens or reflector visible from both streets. The electrical time limiting control is indicated by 6. The unshaded lines indicate controlling circuits. Thus, the vedepresses ramp 1, causing contacts l6 and II to be pressed together, closing circuit between wires I2 and I3. When the wheel leaves ramp 1, spring 9 forces the ramp 1 into an elevated position, breaking circuit between wires I2 and I 3 by separating contacts I and II. The vehicle actuated devices in A Street are connected in parallel. The vehicle actuated devices in B Street are also connected in parallel.

The time limiting control uses several timing mechanisms. One embodiment of such a timing mechanism is shown in Fig. 3. When a source of voltage supply is connected between wires I4 and I5, current flows from wire l4 through wire I6, relay I1, and wire I3, to wire l5, operating.

relay I1. This allows current to flow from wire I4 through adjustable resistance I 9, contact 20, armature 2|, wire 22, wire 23, condenser 24, Wire 25, to wire I5. Thus the voltage of the supply is applied to condenser 24 through resistance I9,

and the voltage of the condenser begins to build up at a definite rate determined by the size of the condenser, the resistance I9. and the voltage of the supply. Shunting condenser 24 is a circuit including a glow tube 26, and a relay 21. The glow tube comprises a bulb containing a suitable gas intowhich electrodes 28 extend. .This tube has such a characteristic that it is normally nonconducting, but when the voltage across its ter- ;minals reaches a certain critical or threshold value, the gas ionizes and becomes a good electrical conductor and will not become non-conducting again until the voltage across its terminals has dropped considerably below the critical ionizing voltage. The voltage of the. supply is greater than the critical voltage of the tube. When the voltage across the condenser is built up to the critical voltage of the tube, the tube suddenly becomes conducting, causing current to flow-momentarily from condenser 24 through tube 26, and relay 21, causing relay 21 to operate. This would effect only a momentary closure of the relay were it not for the locking circuit comprising contact 29, armature 30, and wire 3|, which is established when relay 21 operates. This places relay 21 directly across the supply, and relay 21 remains energized.

The interval elapsing between the application of the supply voltage to wires I4 and I5, and the operating of relay 21, is the period timed by the mechanism. By suitable adjustment of resistance I9, any desired interval may be obtained. When relay 21 operates it may be used to actuate one or more armatures such as 30' in addition to 2 I to touch contact 32.

resistance 33 across the terminals of condenser armature 30. These additional armatures will be used as described below.

Relay 21 remains energized as long as the supply voltage is connected between wires I4 and I5. If the supply voltage is disconnected, the energizing circuits of both relay l1 and relay 21 are interrupted, both relays become deenergized and drop to their deenergized positions. When relay I1 becomes deenergized, it causes armature This shunts adjustable 24., and any energy that may be stored in condenser 24 is dissipated in resistance 33. The rate 01' dissipation of energy may be varied at will by proper adjustment of resistance .33,

Wires I4 and I5 maybe called conveniently the energizing wiresof the timing mechanism and are accordingly marked E-E.

Figs. 5 and 6 combined show a wiring diagram of a traiiic control system the invention. This wiring diagram is arranged symmet rically with respect to an imaginary vertical line through the two figures with the apparatus associated with A Street on the left and that associated with B Street onthe right side oi these figures. The ratcheting mechanisms and associated relays and timer ior the variable incre-' ment feature for the respective streets are shown schematically in Fig. 6.

In the wiring diagram with the various switches, in the positions indicated, the system is so arranged that right of way remains showing on the street which last had right 01' way, in the event that there be no trafllc on either street. Assuming that A Street last bad right oi way, instantaneous operating relay 34 will be energized, thus lighting the A Street green light and B Street red light through wire 35, wire 36, contact 31, armature 38, and wire 39. It will also be noted that timing mechanisms 40 and 4| are energized, and also instantaneous operating relay 42 The action of the apparatus under various traific circumstances will now be described.

Cas I.-S'in fle vehicle approaching on B Street..- Assume a vehicle approaches on B Street actuating one of the vehicle actuated devices located there, closing circuit between wires I2 and I3. The B Street vehicle actuated control devices are connected to wires 43 and 44; thus whenever one of the B Street vehicle actuated devices is actuated, the actuating circuit; oi relay 45 is closed and it operates. This momentarily closes the energizing circuit of relay 46 through wire 41, wire 48, wire 49, contact 50, armature 51 and wire 52. Relay 46 causes armature 62 to touch contact 93, locking in relay 46 through -wire 94, contact 95, armature 90, wire M and wire 62. This locking circuit is necessary because relay 45 operates only momentarily, and were it not for this locking circuit, relay 46 would also operate only momentarily. The operating of relay 46 interrupts the energizing circuit of timing mechanism 46, which had been made through wire 41, armature 53, contact 54, wire 55, contact 56, armature 51, wire 58, wire 59, contact 60, armature BI, and wire 62. Timing mechanism 49, its energizing circuit being broken, allows its relay 21 to drop to its de-energizecl position, releasing armature 63. The energizing circuit of relay 34 which had been made through wire 64, armature 63, contact 65, wire 66, switch I45, wire 61, switch I45, contact 68, armature 69. wire 10, contact 1|, armature 12 and wire 13, is now broken by the deenergized position. Armature 38 separating from contact 31 extinguishes wire 84, wire 85, armature 86, contact 81, wire armature I33, wire'l34 and wire 8|.

88, contact 89, armature 90, wires 9I and 82. 'Iiming mechanism 80 is similar to the timing mechanism shown in Fig. 4, and similarly, E-E represent the energizing wires. Assume that-the resistance [9 In this timing mechanism is adjusted so that the mechanism times an interval of 3 seconds. When relay 34 was de-energized, it de-energized relay 42 because the energizing circuit of relay 42, consisting of wire I3, armature 98, contact 91, wire 98, wire 99, contact I00,

armature 82, and wire 8|, is broken when arma- Y ture 82 separates from contact I00. After timing mechanism 80 has been operating for 3 seconds, its condenser discharges through its tube in the manner described above, and its relay, corresponding to relay 21 operates, causing armature I06 to separate from contact I02, and to touch contact I03. When armature IOI leaves contact I02, it breaks the operating circuit of timing mechanism H and timing mechanism 4I becomes de-energized. The energizing circuit of timing mechanism 4I consisted of wire I04, armature IOI, contact I02, wire I05, switch I08, wire I01, contact I08, armature I09, and wire IIII. When armature IOI touches contact I03, relay III is energized through wire I04, armature IOI, contact I03, switch I48, wire II2, wire I I3, switch I48, contact II4, armature IIB, wire II8, con-'- tact II'I, armature 53 and wire 41. Relay III operates armature I8. Armature I8 separates from contact 1! extinguishing the yellow light and touches contact II8, lighting the B Street green light and A Street red light through wire 18, armature 18, contact I I8, wire H9 and wire I20. The right otway is now being given to B Street and the vehicle-Which approached there may-cross the intersection. Timing mechanism I2I is the mechanism which provides the necessary time for the individuai vehicles on B Street to cross the intersection. This timing mechanism is also similar to the mechanism shown in Fig. 3, E--E representing the energizing wires.

. Assume that the resistance corresponding to resistance I9 is adjusted so that timing mechanism I2I times a period of 10 seconds. The energizing circuit of timing mechanism I2I is made through wire 82, armature SI, contact I22, wire I23, switch I24, wire I23, contact I25, armature 63 and wire 84. It will thus be noticed that this circuit is completed when timing mechanism 40 becomes tie-energized.

Cass II.-Single vehicle approaching on A Street immediately after transfer of right of way to B Street-The action of the apparatus is similar to the action as described under Case I, up to the time right of way is actually transferred to B Street. The single vehicle now approaching on A Street operates, for example, ramp 2. The

ramps in A Street are connected across wires I21 and I28, and thus the vehicle on A Street causes a momentary operation of relay I29. This causes relay 42 to operate by energizing it through wire IIO, armature I09, contact I30, wire I3I, and wire 73. Relay 42 locks itself in through armature 98, contact 91, wire 88, contact I32, Contact between armature I33 an'dcontact I32 is made because when relay I28 operated, it separated armature I09 from contact I08, thus breaking the energizing circuit of timing mechanism 4|, which immediately dropped to its de-energized position. Assuming that only a single vehicle was approaching on B Street, then, after 10 seconds, timing mechanism I2I will operate and armature 90 will separate from contact 95 and 89. In separating from contact 89, armature 90 breaks the energizing circuit of timing mechanism 80 which becomes de-energized, causing armature IM to leave contact I03. This deenergizes relay III, which allows armature F3 to separate from contact II8, extinguishing the B Street green light and A Street red light. At the same time armature I8 touches contact 'I'I, lighting the yellow light as described above. In de-energizing, relay III allows armature 6| to touch contact 80, which re-estabiishes the energizing circuit of timing mechanism 40. Timing mechanism 40 is similar to the mechanism shown in Fig. 4; and we shall assume that its resistance, corresponding to resistance I9, is so adjusted that the mechanism times a period of 3 seconds. After being energized for 3 seconds, timing mechanism 40 operates, separating armature 63 from contact I26, and allowing armature 33 to touch contact 88. .In separating from contact I26, armature 83 breaks the operating circuit of timing mechanism I2I, which becomes de-energized. At the same time, armature 83, in touching contact 85 energizes relay 34. Relay 34 operates arma ture 38, which leaves contact I4, extinguishing the yellow light, and touches contact 31, lighting the A Street green light and B Street red light, and the right of way is again being given to A Street and the vehicle which approached there may cross the intersection.

Theabove two cases describe transfer of right of way from one street to another in response to a vehicle approaching on this street where right of way is not being given. It will be noticed that once a vehicle has been given right of way, it will retain right of way for a certain minimum period, for example, 10 seconds; and even though a vehicle approached on the other street, right of way cannot be taken away until the end of this minimum period which we assume is sufilcient time for the vehicle to cross the intersection. If all trailic has ceased, then the timing mechanism which provides this minimum period, (for street Athis would be timing mechanism 4i), is in its operated condition, and should a vehicle approach on the other street, right of way will be transferred immediately. If trafilc has not ceased, the above mentioned timing mechanism will not be in its operated condition, and should a vehicle approachon the other street, it must wait until this timing mechanism has operated.

Cass III.Single vehicle approaching on B Street followed within ten seconds by a second vehicle on B Street-Assuming the right of way is being shown to A Street and there is no traffic on A Street, then the first vehicle approaching on B Street .will transfer right of way to B Street as described in Case I. Ii 9. second vehicleapproaches on B Street, actuating either ramp I or 3, this will cause relay 48 to operate momentarily breaking circuit between armature and contact I22. This will break theenergizing circuit of timing mechanism I2I. We have assumed that timing mechanism I2I times a period of seconds. Assuming the second vehicle to have approached within 10 seconds from the time the.

first vehicle approached, condenser 24 of this tlmingmechanism will not be charged up to the critical voltage of tube 28, andrelay 21 will not have operated. The breakingof the energizing circuit de-energizes relay I1 and the charge which has accumulated on the condenser will be dissipated 'in resistance 33, as described previously. Relay 45 is of course energized only for a short time, and consequently the energizing.

circuit of timing mechanism I2I is immediately re-established. But it will be noticed that condenser 24 has been de-energized, and consequently a full 10 seconds must elapse before the condenser will again be charged to the critical voltage of tube 28. The operation of the system under Case III has shown that right of way cannot be taken away from B Street once it has received it, until timing mechanism I2I has operated. Thus, whether or not, in the meantime, a vehicle has approached on A Street, the second vehicle that approached on B Street receives a full 10 seconds in which to cross the intersection. It is apparent that this operation will be repeated if additional vehicles approach on B Street. As soon as vehicles cease approaching on B Street, timing mechanism I2I will, after 10 seconds have elapsed since the last actuation of either ramp I or 3, operate, and assuming a vehicle to have approached on A Street, the right of way will be transferred to A Street, as described under Case'II. Once right of way has been transferred to A Street, the operation of the system, should more vehicles approach on A Street, is precisely as described above. Relay I29 performs the same function for A Street that relay 45 performs for B Street; and, similarly, timing mechanism 4I operates when right of way is being given to A Street, just as timing mechanism I2I operates when right of way is being given to B Street.

In describing Case III, it was assumed that after right of way was'transferred to B Street, a vehicle approached on A Street. If no vehicles approach on A Street, then after the last car has passed B Street, timing mechanism I2I will operate and right of way will simply remain on B Street. This is because, even though the energizing circuit of timing mechanism 40 is interrupted when armature 90 separates from contact 89, timing mechanism 80 remains energized because power continues to be applied through wire I35, contact I36, armature 12, and wire 13. This is because, since no vehicle has approached on A Street, relay 42 is de-energized. Ii vehicles should again come on B Street, timing mechanism I2I will again be deenergized, as

described above. The B Street trafllc will again be protected and it cannot lose right of way until all of it has passed the intersection. It is apparent that as long as no vehicles approach on A Street, B Street traflic can retain right of way indefinitely.

CAsl: IV.-C0ntinuous traflic on B Street with a vehicle waiting on A Street-When this condition occurs, timing mechanism I2I will be continually de-energized or re-set by the B Street vehicles, and right of way would remain indeflnitely on B Street. This is permissible if there is no traflic on A Street. But should vehicles approach on A Street, there must be some limitation to the length of time B Street can continue to hold right of way after vehicles have approached on A Street. This is accomplished with timing mechanism I31. This timing mechanism isagain similar to the type shown in Fig. 3. and we shall assume that its resistance It is so adjusted that the mechanism times a period of 30 seconds. This timing mechanism does not beg-in to operate until a vehicle approaches on A Street. When this happens, relay 42 becomes energized and current flows from wire 13, through armature 12, contact 1I, wire I38, the energizing wires E-E of timing mechanism I31, wire I25, contact I28, armature 63, and wire 64. It will furthermore be noticed that this timing mechanism is not re-set by vehicles on B Street, and once energized, uninterruptedly continues to time until the end of its timing period, for example, 30 seconds. Assuming B Street traific to be continuous, then after 30 seconds, timing mechanism I31 will operate armature 86, separating it from contact 81. This de-energizes timing mechanism 80 which in turn de-energizes relay III, and right of way is transferred to A Street as described above under Case 11. The difference is that relay 46 remains energized because its locking circuit continues to be made through contact 95 and armature 90, since timing mechanism I2I has not been energized long enough to operate. Thus, after right of way is transferred to A Street, relay 46 is energized. which is equivalent to the approach of a vehicle on B Street. The system thus provides that without requiring an additional actuation of either vehicle actuated control I or I, right of way will return to B Street as soon as traflic on A Street permits. This procedure is necessary because a vehicle may approach on B Street within a second or two from the time right of way is going to be taken from B Street, and not having had suinclent time to cross .the intersection, these B Street vehicles would be stranded. The system is thus arranged so that when right of way is transferred, due to the operation of timing mechanism I2I, relay 48, during such a transfer, be-

comes de-energized. But, should timing mechanism I 31 transfer right of way, relay 44 will not become tie-energized, the right of way will thus be recalled to B Street, so that vehicles on B Street which did not receive a full 10 seconds in which to cross the intersection, will be given of way is given to a particular streetnin response to vehicles approaching there, each vehicle receives a certain protection period from the time it actuates the ramp in the street, during which it may cross the intersection, and is protected against opposing traflic. If a vehicle approaches on the street where the stop sign is being given,

right of way will be transferred to it immediately if .traflic has ceased on the intersecting street." If traiflc has not ceased, this vehicle must wait until the last vehicle on the intersecting street has had a full minimum period in which to cross the Intersection. However, vehicles do not have I time, thecontinuous traflic on the opposing street is interrupted to allow the waiting vehicle or vehicles to cross the intersection. Thamtem, however, is left in such aconditmmthat zero voltage to the residual voltage.

In describing the operation of the embodiment of the timing mechanism shown in Fig. 3, it was stated that the rate of discharge or re-set could be varied at will by proper adjustment of resistance 33. This resetting occurs whenever the energizing circuit E-E is interrupted. While the rate of discharge may be determined by resistance 33, the actual amount oi discharge depends upon the length of time the energizing circuit is interrupted. If this time is long, practically all of the stored energy will be dissipated in resistance 33. Thus when the energizing circuit is re-established, charging of condenser 25 will start with practically no stored energy in the condenser, and the time required to charge the condenser will be the time necessaryto charge it from zero voltage to the critical voltage of tube 26. If the time of reset is short, condenser 25 will not be completely re-set, and thus when the energizing circuit is re-established, charging of condenser 24 will start with. a residual voltage on the condenser, and the period timed by the mechanism will be the period necessary to charge condenser from that voltage to the critical voltage of tube 26. The timed period will be shorter by the amount of time that would have been necessary to charge condenser 26 from it is thus apparent that the amount of re-set depends upon the length of time the energizing circuit is intempted...

The above is the action of the apparatus if the energizing circuit is always interrupted when condenser 2% has been charged to some particular voltage. In practice, as will appear later, the interrupting of the energizing circuit may occur at all sorts of different voltages. Considering the operation of the device more in detail, it will appear that actual amount of discharge, while depending upon the length of time the energizing circuit is interrupted, also depends upon the voltage to which the condenser has been charged when the energizing circuit is interrupted. Thus,

'for example, a re-setting impulse of a certain length of time, if occurring when the voltage of the condenser is 180 volts, re-sets the condenser to a voltage of 120; a re-setting impulse of the same length or time, if occurring when the condenser voltage is 150 volts, will re-set the con= denser to 100 volts. It thus appears that for a particular setting of resistance 33, re-settlng impulses of a certain length of time will re-set the voltage of the condenser to a certain fraction of its voltage; This memes apparent from a consideration of the discharge equation of a corn: denser. This equation is:

Eu is the voltage of the condenser when discharge was started; Et is the voltage of the condenser after t seconds; e is the constant value 2.7183; E's is the value of the resistance 33; and C the capacity of the condenser. C is of course fixed, and R is assumed set at some particular value. Thus it is obvious that for a particular value of t, the condenser will always be discharged to the same portion of the voltage.

Referring now to Fig. 2, it will be noticed that the vehicle actuated device consisting of ramp 1 is so arranged that circuit between wires l2 I8 is closed during the time the wheel of the vehicle is on ramp 7. Since the length of time the ,wheel is on the ramp depends upon the speed of the vehicle, circuit between wires I2 and [3 will :6

be closed for a short period of time, if the vehicle is travelling rapidly, and for a long period of time if the vehicle is travelling slowly. Actuation of either ramps l and 3 operates relay 5,

and since this relay is directly connected to the i 1,

circuit closed by ramps I and 3, relay 45 will be energized only while the wheel of the vehicle is actually on the ramp, and consequently the length of time armature is separated from contact I 22 depends entirely upon the speed of 'lo length of time which depends entirely upon the speed of the vehicle causing such interruption. Referring now to the above description of the operation of the timing mechanism, it becomes apparent that timing mechanism I2I, although giving the first vehicle a full 10 seconds in which "26 to cross the intersection, gives succeeding vehicles an additional period which is dependent upon their speed, and consequently, succeeding vehicles are given just suilicient time to cross the intersection, instead of receiving a full, unnecessarymo 10 seconds. The faster the vehicle travels, the less the re-set, and consequently the less is the time given the vehicle. But, the faster 8. vehicle travels, the less time it needs.

The above would be the action if succeed lng gg vehicles continually approach just before timing mechanism I2! is about to operate and separate armature 90 from contacts 89 and 95. In practice, traflic rarely approaches in just that manner. For example, the second car may 8.131301084211240 within a second or two from the time the first car approached. Thus, ii. there were no re-setting at all, the second car would receive possibly 8 or 9 seconds in which to cross the inter? section, which might be ample. But, the apparatus automatically takes care of Just such a condition. II the second car approaches, say, after 2 seconds, timing mechanism |2l will have been energized for only 2 seconds and the voltage built up in its condenser will be quite small. 5

Since, as explained above, the re-settlng does not reduce the voltage of the condenser by a certain number of volts, but instead reduces the voltage by a certain portion of the voltage built up, the

amount of re-set will be very small, and the addltional time given the secondvehicle, very small.

Timing mechanism 6!, constructed similar to timing mechanism l2! performs the same operation for street A.

Connection II.--The operation described above 00 occur when the various switches are in the positions shown in Figs. 5--6. It may be seen from an inspection of these figures that if switch IM is closed, relay 42 is continuously energized, thereby causing the right of way to return to A Street 05 spection of Figs. 5-6 that if the switches are as shown, except that switch it is closed, the operation is as described under Connection II, except that the conditions described for A Street and B Street are interchanged.

Connection IV.It can be seen that with m ramp insaid street so that-the switches MI and I42 closed, the right of way is granted alternately to each street and is held by each street for any period between 10 and seconds. If no vehicles actuate the ramp in a 8 particular street during a period of 10 seconds, the 10 second timing mechanism functions to yield the right of way 10 seconds after it is granted. If, on the other hand, when said street is given the right of way, vehicles operate either second timing mechanism continually re e t, he 30 second timing mechanism functions to yield the right of way 30 seconds after it is granted,

Connection V.-'Ihe circuit is so arranged that u if, for any reason, it is desired to disconnect the traflic actuated means, this can be accomplished by throwing switches I43 and IE4 to their down positions. Under these conditions, relays 42 and 46 are continuously energized and the energizing '20 circuits of timing mechanisms 4I and I2I are continuously interrupted. The system will then function to give right of way alternately to A Street and B Street for periods of 30 seconds each.

Connection Vl.-If it is desired to operate a system by hand, this can be accomplished by using switches I and I48. If both switches are open, relays 34 and III are de-energized and the yellow light will be shown to both streets,

as as described previously. ,If switch I45 is then thrown to the down position, relay 34 will be energized and the A Street green light and B Street red light will be shown. By again opening switch I45, the yellow light will again be .8 shown to both streets. If, then, switch us is thrown to the down positiomrelay III will be energized, thus lighting the B Street green light and A Street red light. By opening switch M6, the yellow light will again be shown to both streets. Thus the lights can be operated manually in any desired manner.

Connection VII.By closing switch I41, or by applying power to the two wires marked To fire headquarters, this will, through wires I49 and I50 energize relay I48. This will operate armature 69 and II5, separating them from contacts 68 and H4 respectively. This interrupts the energizing circuits of both relay 34 and III and consequently both of these relays become 59 de-energized. This lights the yellow light visible right of way is transferred from A Street to B Street, timing mechanism 80 times the warning interval during which the warning signal or yellow light is shown. As mentioned before, this timing mechanism is similar to the one shown in Fig. 4, and its resistance I9 was assumed adjusted so that it timed a period of 3 seconds. There is one slight difference in its construction from that of Fig. 3, and its complete wiring diagram is shown in Fig. 4. This difference consists in wires I5I and I52. Wire I52 is connected to one end of resistance I9 as shown, while wire ISI may be' adjusted along resistance I9 by tap I83. If circuit between wires IiiI and I52 is be, for example, 1 second. It will be noticed, furthermore, that if right of way is transferred from A Street to B Street, through the opera.-

is tion of timing mechanism 4|, then the circuit between wires Idi and I52 is closed because timing mechanismdi, in operating, causes armature I56 totouch contact I55. Thusthe timing mechanism will provide a short warning period, namely, 1 second. If the transfer is caused 5 by the operation of timing mechanism I39, then circuit between wires i5! and IE2 is not closed, and the warning signal provided by timing meg'hanism 80 will be 3. seconds in length because no portion of its charging resistance has w been shunted out.""When the transfer of right of way is from B Street to A Street, timing mechanism MI performs in a manner similar to timing mechanism 80. In this case the shunting out of a portion of the resistance is accomit plished through wires I56 and IB'I, armature I58 and contact I59.

The foregoing indicates that when right of way is transferred through the operation of either 1 timing mechanism di or timing mechanism I2I,-' the following warning period will be short, namely, 1 second. 'If the transfer is caused by the operation of either timing mechanism is? or I39,

. the following warning period is long, namely, 3

seconds. This variable warning signal is in ac-' 25 cord with tramc requirements. When traiilc has ceased, on A Street for example, timing mechanism 4I transfers right of way to B Street, and since traiiic has ceased on A Street, no longer warning signal need be given because there are ao no vehicles on A Street to be warned. The action is similar when timing mechanism 926 transfers right of way from B to A Street. If timing mechanism 839 transfers right of way from A Street to B Street, it means that con- 35 tinuous A Street trafilc is being interrupted, and consequently a longer warning signal should be given so that the vehicles in A Street may-have ample time to be brought to a stop. The action is similar when timing mechanism Ii'i transfers-egg a right of way from B to A Street. It will be noticed that the mechanism provides a long or a short warning period in accord with the needs of the trafllc.

Connection IX.--If all the switches are as is shown in Figs. 5-6, except that switch let is closed, then as soon as right of way is given to B Street, armature 6| touches contact IN and the energizing circuit E-E of timing mechanism I62 is made through wire- I63, switch I60, wire Sign contact IBI, armature ti and wire 52. This timing mechanism is similar to the one shown in Fig. 3, and we shall assume that its resistance I9 is so adjusted that it times a period of 2 minutes.

If right of way is taken away from B Street &5 before the end of 2 minutes, the energizing cir cult of timing mechanism W2 will be interrupted,

its condenser will be discharged, and another 2 minutes of continuous B Street right of way must be shown before timing mechanism I82 willw operate. Assuming there is no A Street trafllc, then right of way would remain on B Street indefinitely, were it not for timing mechanism I62. After right of way has been showing for 2 minutes on B Street, timing mechanism I62 as operates, causing armature I65 to touch contact I66. This through wire I83, contact I66, armature'ISB, wire I81 and wire I3 energizes relay 52.

It will thus be noticed that the operation of timing mechanism I62 operates relay 62, thus pergo forming the very same function that a vehicle approaching on A Street would have performed.

If, when relay 62 operates, B Street tramc has ceased, right of way will be transferred to A Street. If B Street traflic has not ceased, then rag right of way will eventually be transferred, as described above in the several cases, depending upon traffic conditions in B Street. We thus have a system which. in the event there is no traffic on one street, does, after a certain length of time, shift right of way to that street in order to allow pedestrians to cross. An additional important featureis that it does not arbitrarily transfer right of way at the end of the 2 minutes. It merely puts in a call on the street where the red light is being shown, and the system then takes care of that call just as though it had been caused by a vehicle approaching on A Street. The fun damental object of this system is to operate the signal lights in such a way that tramc is. controlled most emciently. Timing mechanism I82 does not disrupt that operation but merely insures that right of way will eventually be given to an opposing street even though there be no traffic upon it, in order to allow pedestrians to use the intersection.

If switch I68 is closed, timing mechanism I68 will be energized when right of way is given to A Street. This is accomplished through wire 8|, armature 82, contact I10, wire I1I, switch I68, energizing circuit E--E and wire I12. Timing mechanism I68 is similar to timing mechanism I62, and performs the same function for B Street that timing mechanism I62 performs for A Street. When timing mechanism I68 operates, it closes contact between armature I14, and contact I13, and thus through wire I12, contact I13, armature I14, wire I18, wires 48 and 41, operates relay 46. Right of way is now being called to B Street and will be transferred, as described above in the several cases. Briefly reviewing the operation, it will be noticed that when right of way has been showing continuously on one street for 2 minutes, right of way is called to the other street, and will be transferred to that street after not more than 30 seconds.

Connection. X.--In all of the above description, it was noticed that timing mechanism 4I began to operate as soon as right of way appeared on A Street. Experience has shown that it is, in most instances, necessary to place the vehicle actuated devices quite some distance from the intersection. This occurs because vehiclesshould register their presence some time before they reach the actual intersection. This will allow the mechanism to either give them time to cross the intersection, or if right of way is to be taken away from the approaching vehicles, give them ample distance in which to stop. Suppose, for example, that the vehicle actuated devices are placed 150 feet from the intersection. Assume now that several ve hicles approach on a street where the red light is showing, and assume also that they do not receive right of way immediately and are forced to stop. Eventually, of course, right of way will be transferred to that street and the vehicles will be given time to cross the intersection; in this case, 10 seconds. If all the vehicles got into motion at once, this time would be ample because the period provided should be suflicient to allow a moving vehicle, which has just actuated one of the vehicle actuated devices, to cross the intersection. However, the vehicles will not all move simultaneously. if, say, 10 vehicles are waiting, approximately 15 seconds will elapse before the last vehicle in the line gets into motion. Assuming there are no further operations of the vehicle actuated controls, the vehicle protection timing mechanism on that street will not be re-set and will, after 10 seconds, transfer right of way to the opposing street. This obviously will occur some time before the last vehicle in the line has begun to move, and several of the vehicles will be stranded, without, however, leaving the system in such a condition that right of way will again be given to the stranded vehicles without requiring further actuation. It is thus necessary to provide an initial timing period long enough to allow all of the vehicles to get into motion, and furthermore, not to start the vehicle protection timer until the end of this initial period. If the system is operated in this manner, it will effectively take care of the time required to allow waiting vehicles to getdnto motion.

This initial timing period is provided by timing mechanism I16. The structure of the actual timing mechanism is similar to the one shown in Fig. 3. When power is supplied to the two wires EE, current flows through wire I11. relay I18, and wire I18, operating relay I18. This causes armature I to touch contact I8I, and condenser I82 would be charged through resistance I83. The amount of this resistance is variable by means of contact I84. shunting condenser I82 is a glow tube I83 similar to the one previously described. When condenser I82 is charged to the critical voltage of tube I83, the tube becomes conducting and the energy stored in I82 discharges through tube I83 and relay I84, momentarily operating relay I84. This relay locks itself in through contact I85, armature I86 and wire I81. Contact I84 is mounted on a rack-arm I85, mounted so that it can slide longitudinally. This rack-arm is pulled against stop I86 by tension spring I81: When switch I88 is moved so that it touches contact I88, current flows from wire I80 through magnet I8I, switch I88, contact I88, and wire I82; and magnet I8I will be continuously energized. Magnet I8I attracts armature I83, pivoted at I84. The armature I83 is hinged at I85, and when attracted by magnet I8I, causes finger I88 to engage the teeth I81 of rack-arm I85. Thus if rack-arm I86 is moved to the left, the mechanism operated by magnet I8I will prevent its return motion. It will furthermore be noticed that moving rack-arm I88 to the left increases the resistance in the charging circuit of condenser I82. Assume that the rack-arm is moved so that timing mechanism I16 times a period of 10 seconds. In addition switch I06 must be open.

When right of way is being given to B Street, relay 34 is de-energized and current flows from wire 38, armature 38, contact I88, wire I88, relay 200 and wire 20I, operating relay 200.- Relay 200 operates armature 202 and locks itself in through contact 203, armature 202, wire 204, contact 208, armature 206 and wire 201. Assume that one or more cars are waiting on A Street, and right of way is about to be transferred from B Street to A Street. In the above description it will be remembered that timing mechanism 4| begins to operate as soon as right of way is transferred to A Street. With switch I06 open, however, the energizing circuit of timing mechanism 4! is interrupted and will not be closed until relay 208 operates, which will close the energizing circuit of timing mechanism 4I, through wire 208, armature 2I0, contact 2, and wire 2I2. Relay 208 does not operate immediately as will appear from the following description. When right of way has been transferred to A Street, relay 34 will be energized, which allows current to flow from wire 38 through armature 38, contact 2I3, wire 2, wire I11, relay I18, wire I18, contact 2I6, armature H8 and wire 20i, operating relay I18. This aiaas'ri establishes the charging circuit of condenser 182 through wire 80, armature 32, contact 2I3, wire 2%, condenser I82, armature 180, contact IN, contact 186', resistance I83, contact 2I5, armature 2I5, and wire 20L Thus, the voltage of the supply is applied to condenser I02 through resistance I33, and the voltage of the condenser will begin to build up. As assumed before, 10 seconds will elapse before condenser I82 is charged up to the critical voltage of tube I03. Although right of way is being given to A Street, timing mechanism M has not begun to operate, and the vehicles waiting on A Street are given opportunity to get into motion and start across the intersection. They are in no danger of having timing mechanism 4| prematurely take away right of way. After 10 seconds have elapsed, condenser I82 reaches the critical voltage of tube I83 and the energy stored in condenser I82 discharges through tube 183 and relay I88, operating armature lBB which locks in relay I82 through contact I05, armature I85, wire. I81, contact 2I5, armature 2H5, and wire 21". Relay I84 also operates armature 211, causing it to touch contact 2I8. This allows current to flow from wire 2 I9,through contact 210, armature 241, wire 220, relay 208 and wire 201, operating relay 208. This closes contact between armature M and contact 2! I, completing the energizing crcuit of timing mechanism 2!.

It thus appears that the waiting vehicles have been given a period of 10 seconds-in which to get into motion, and after this period, timing mechanism M provides the usual protection period, which of course is resettable by additional vehicles approaching on A Street. The action from now on is just as described in the above cases. When relay 202 operates it causes armature 2I0 to touch contact 22 I, locking in relay 208 through contact 22 I, armature 2), wire 200, wire I05, contact I02, armature I01 and wire I04. At the same tirne relay 208 causes armature 208 to separate from contact 205, interrupting the locking circuit of relay 200 which becomes de-energized. When relay 200 becomes de-energized, armature 258 separates from contact 215, interrupting the energizing circuit of timing mechanism 16, and relay I18 becomes de-energized. This shunts adjustable resistance 222 through contact 223 and armature I80 across the terminals of condenser I82, and any energy stored there will be dissipated in resistance 222. If trafilc approaches on B Street, then eventually right of way will be transferred to B Street. The moment A' Street loses right of way, relay 34 becomes de-energized, establishing the energizing circuit of relay 200, which operates. The locking circuit of relay 200 is not completed until the end of the warning period. At the endof this period, timing mechanism 80 operates, separating armature IOI from contact I02 which interrupts the locking circuit,

of relay 208 which becomes de-energized, allowing armature 206 to touch contact 205. And the locking circuit of relay 200 is complete. The mechanism has now returned to the condition at the beginning of operations.

Timing mechanism 224 performs the same function for B Street that timing mechanism I15 performs ior A Street. Similarly switch I24 must be opened. Switch 225 when moved to touch contact 225 causes magnet 221 to be continuously energized through wires 228 and 229. The armature 230, operated by magnet 221, is similar to the armature operated by magnet IQI, and is arranged to engage the teeth 23I of rackarm 232. This rack-arm is pulled toward stop 233 by spring 234. When right of way is being given to A Street, relay H1 is de-energized, and through wire 235, wire 235, contact 231, armature 10 and wire 19, energizes relay 238. This relay locks itself in through contact 239, armature 260,

wire 221, contact 242, armature 223 and wire 254.

When right of way has been transferred to B Street, current flows from wire 19 through armature 18, contact 245, wire 226, relay 221, wire 248, contact 249, armature 250, and wire 235, operating relay 221. This establishes a circuit from wire 19, armature 18, contact 265, wire 2 28, condenser 25L armature 252, contact 253, contact 254, relay 255, contact 240, armature 250 and wire 235. Assume that rack-arm 232 is so adjusted that the amount of adjustable resistance 255 is of such a value that 10 seconds are required to charge condenser 251 up to the critical voltage of tube 250. After 10 seconds have elapsed, the energy stored in condenser 25! through tube 256 and relay 251. Relay 251 looks itself in through contact 258, armature 255 and wire 260. At the same time a circuit is established through wire 28!, contact 252, armature 283, and wire 280, through relay 205, and. through wire 2. When relay 265 operates it looks itself in through contact 266, armature 201 and wire 268, at the same time through contact 260 and wire 210 completes the energizing circuit of timing mechanism I21- The operation of the device from this time on is similar to the operation of timing mechanism I15, except that the functions for Aand B Streets are interchanged.

The above connection provides for an initial period during which vehicles may get into motion. While this may be satisfactory, in a great many installations, the device may occasionally be inefiicient because the timing period, although adjustable manually, is fixed. Thus if, for example, 5 vehicles are waiting, the second period may be just right. If more than 5 are waiting, a longer period may be desirable, and then again, if less are waiting, a shorter period would be ample. Thus it is desirable to provide an initial period that is proportional to the number of vehicles waiting. This may be accomplished on A Street, for example, by closing switch 21I and moving switch I08 so that it touches contact 212. When right of way is being-given to B Street, and no vehicles are waiting on A Street, relay 200 will be energized, as described previously, and so will magnet I9I, although the energizing circuit of magnet I9I is somewhat different,.being made through wire 213, contact 2I5, armature M5, and wire 20L As will appear later, rackarm I85 is resting against stop I86. Every time a vehicle approaches on A Street, it momentarily operates relay I29, allowing current to flow from wire 214, contact 215, armature 216, wire 211, contact 218, armature 219, wire 200, switch 21I, magnet 28l, and wire I90, momentarily operating magnet 28L This attracts armature 282 which is similar to the armature operated by magnet IOI. Finger 283 engages the teeth of rack-arm I85, notching the rack-arm forward by the distance of one tooth. Magnet I9I is so arranged that when the rack-arm is moved forward the distance of one "tooth, finger I90 engages the teeth and prevents the return motion of rackarm I85. Thus, magnet 28I is momentarily en ergized every time a vehicle causes relay I29 to operate, andthe rack-arm I85 is moved a distance proportional to the number of vehicles that have approached on A Street, while right of way discharges is being given to B Street. This provides that, since contact I84 moves with rack-arm I85, the amount of resistance I831 in series with condenser I82 is proportional to the number of vehicles waiting, and when timing mechanism I19 begins to time, the period timed by it will be proportional to the number of waiting vehicles. The operation of the device otherwise is the same. At the end of the period timed by mechanism I16, relay I84 operates and thus causes relay 208 to operate, all as described previously. At the same moment, relay 200 becomes de-energized and armature 2I6 separates from contact 2I5. This de-energizes timing mechanism I16; but, in addition, also de-energizes magnet I9I, allowing finger I96 to move out of engagement with the teeth of rack-arm I85, and rack-arm I85 is pulled against stop I86 by spring I81. Thus the mechanism has returned to its starting position, so that the next time vehicles register their presence on A Street while B Street is being given right of way, will again provide themselves with an initial period proportional to their number. It will furthermore be noticed that when right of way appears on A Street, armature 219 separates from contact 218, interrupting the notching circuit of magnet 28I, and thus the initial period will not be increased by further vehicles registering on A Street.

An enlarged and more detailed diagrammatic view of the ratchet mechanism is shown in Fig. '7. In this enlarged view. in order to illustrate both energized and deenergized conditions of the electromagnetic devices, the ratchet actuating magnet I is assumed deenerglzed and its armature 292 is shown in deenergized non-actuated position with finger 292 disengaged from the rack teeth I91, and the ratchet holding magnet "I is shown in its energized condition with finger I96 engaging the teeth I91. For this view it may be assumed that switch 21I of Fig. 5 is closed and switch I88 of Fig. 5 is in engagement with'contact 212 for example and the rack I85 is shown in a partly advanced position away from stop I96 to illustrate its condition after several ratcheting actuations by trafilc.

The operation of timing mechanism 224, which provides the initial period for B Street, can be adjusted similarly by closing switch 289 and moving switch 225 so that it touches contact 285. Thus, whenever a car operates one of the B Street ramps, relay 45 operates momentarily, allowing current to flow through wire 296, contact 281, armature 289, wire 289, contact 290, armature 29I, wire 292, switch 284, magnet 299, and wire 229. Thus, magnet 293 is operated every time relay 48 operates. Magnet 299 operates armature 299 notching rack-arm 232 in a'manner similar to the notching of rack-arm I85. It will again be noticed that vehicles registering on B Street, after right of way has appeared on B Street, do not increase the initial period because the notching circuit is interrupted at contact 298 and armature 29 I which are caused to separate when relay III operates.

While the above mechanism provides for an initial period. that ls proportlonal to the number of vehicles waiting, it may, under certain circumstances, be desirable to increase the initial period even after right of way has appeared on that particular street. The foregoing discussion shows that the initial period is proportional to the number of vehicles waiting, and presumably the last waiting vehicle has just started to move at the end of the initial period. But if further vehicles have registered their presence, then sufllcient time has not been allowed for them to get into motion. And thus it may be desirable to increase the initial period even during timing of the initial period. This may be accomplished for A Street by closing switch 295, and as a consequence the notching circuit is not interrupted when right of way appears on A Street. If further vehicles approach on A Street, they will continue to operate magnet 29I, moving rack-arm I85 so as to increase the charging resistance. provided to perform the same function for B Street.

From the foregoing, it will be seen that a traflic control system is provided which operates in such a way that:

1. The right of way is given successively to several trafllc lanes in an order which may be predetermined, but in such a way that the length of time one lane retains the right of way Is dependent upon either the approach of vehicles in said lane or upon approach of vehicles in one or more other lanes, or upon both.

2. That a trafilc lane which does not require the right of way cannot hold it to the disadvantage of one which does.

3. That a vehicle whose progress is prevented by continuous stream of opposing trafilc may not be required to wait more than a predetermined period of time, and that not later than the end of said predetermined period of time said vehicle is given right of way for a period of time sufllcient for it and {ollowing vehicles to cross the intersection.

4. That interfering lanes of traflic shall not be given right of way simultaneously.

5. That a vehicle which has passed an actuating means is protected against opposing trailic for a period of time sufiicient to permit said vehicle to pass the intersection of the traflic lanes.

6.,That a vehicle which approaches an intersection on any lane of traflic is given immediate right of way on condition, and only on condition that there be no opposing trafilc in or immediately approachlng the intersection.

'7. That when a vehicle is not given immediate right of way or has right of way taken from it, before it has had sufficient time to cross the intersection, the system will be left in such a condition that right of way will return to the dneiltayed vehicle as soon as traflic conditions per- 8. That periodically right of way shifts to another lane even though there be no vehicular tramc on that lane, in order to allow pedestrians to cross the intersection.

9. That when the signal means and timing system is disconnected fromthe trafflc actuated means, right of way may be given successively to the various trafllc lanes according to a predetermined sequence and to each lane for a predetermined time interval. v

10. That the'signal means may be disconnected from the trafllc actuated means and timing system and be operated manually.

11. That the timing system may be actuated to give a special signal for emergency use.

12. That the warning signal may be interposed between right of way and stop signals, the timing of said warning signal being in accord with the tramc conditions existing at the moment.

13. That each vehicle is protected against op- Speedposing tramc for a period commensurate with its Switch 288 is 14. That if one or more vehicles, after passing the actuating means, do not receive right of way immediately, they will be protected against opposing tramc when they do receive right of way, for a period of time sumcient to allow the last of the waiting vehicles to get started.

Summarizing certain of the salient features of the present invention, it will primarily be understood that an extremely efllcient trafilc control system is herein provided and by means of which among others, the-several objects of the, invention as specifically afore referred to are achieved. Contributing to the advantages of the applicants embodiment of their invention are a numberof factors which for the purpose of convenience may be identified (a) as variable amber, (b) periodic call, (0) variable increment, and (11) speed proportional control. It will be understood that, as indicated at the beginning of this specification, the present invention is primarily concerned with the variable amber" and the variable increment" among these several factors and not with the periodic call and "speed proportional control" factors, but that the latter two factors may in some circumstances be included in traific control systems embodying either or both of the former two factors.

Dealing primarily with the question of variable amber, it will be understood that in the case of traffic approaching the intersection along one vehicle lane, and with no trailic in the second vehicle lane, there will be no necessity for a relatively delayed amber or transfer period. Accordingly, and by means of the present invention, the system will serve to transfer right of way to the vehicle lane over which tramc is approaching the intersection with a minimum delay period. On the other hand, where need for this delay period exists, as for instance, where there is a continuous stream of tramc along the vehicle lane which has the right of way and vehicles on the intersecting lane are awaiting the right of way, the transfer of right of way will only be completed after a maximum 1. e. a three second delay period.

Dealing with the question of periodic call, it will be observed that in one form of the present embodiment, a functioning of the vehicle actuated control in effect occurs periodically even in minute timers in the event of continuing traffic along one lane have their functioning qualified by the thirty second timer. The former permitting the initiation of functioning of the latter after two minutes have elapsed. In the case of traffic over neither lane, the two minute timers would of course operateperiodically to permit Y pedestrians to traverse the intersection without fear of trafilc. It will, .of course, be appreciated that this periodic call is entirely qualifledin the case of continuous traffic approaching the intersection over both vehicle lanes.

With regard to the variable increment feature, it is understood that as previously brought to be transferred before the last of the vehicles could negotiate the intersection. This difficulty, however, is anticipated by means of the present invention in that a timer functioning after right of way has been accorded such a vehicle group does not begin actually until a time period has elapsed proportionate to the number of vehicles which are awaiting the transfer of right of way. Accordingly, the last vehicle of this group will still be accorded a minimum right of way time period to negotiate the intersection. As a practical matter, it may of'course be in many instances desirable according to the present invention to manually set this portion of the apparatus to approximate for this condition, but in any event, the time factor will be adequate and the system will take into account those vehicles arriving just after right of way has been accorded and which vehicles necessarily slow down as they become part of the group which is negotiating the intersection.

With respect to the speed proportional control, it will be understood that with this feature in the present embodiment, the timer resetting is not simply effected in an arbitrary manner which might in one instance result in undue delay to transfer of right of way and in another instance result in the transfer being effected at such an early moment as to trap a vehicle at the intersection, but that the resetting of this timer will actually be in proportion to the speed of the vehicle which is approaching the intersection. 4

Obviously, one or more of these factors might under certain instances be dispensed with and the several units of the-apparatus while preferably embodying a construction substantially of the type illustrated and described, might be changed in numerous respects without departing from the spirit of the invention as defined by the claims.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A trafllc control system including, in combination, a signalling means adjacent the point of intersection of vehicle lanes to accord and interrupt right of way to traffic over said vehicle lanes, a timer controlling the operation of said signalling means. controllers ada ted to be the absence of vehicles. More particularly as set p act ated by trafllc in said lanes and connected to said timer to govern the functlonings of the latter, said timer being potentialized during right of way signalling indication to vehicles traversing one lane to transfer such right of way to a second vehicle lane in which controller actuation has occmred and to accord a minimum period of right of way 'to the said second vehicle lane.

- and means acting in response to controller actuation in the second lane to extend such minimum period proportional to the number of vehicles awaiting such right of way and which have actuated said controller.

2. A traffic control system including, in com bination, a signalling means adjacent the point of intersection of intersecting vehicle lanes to accord and interrupt right of way to trafllc over said vehicle lanes. a timer controlling the operation of said signalling means, controllers adapted to be actuated by trafflc in said lanes and connected to said timer to govern the functionings of the latter, said timer being potentialized during. right of way signalling indication to vehicles traversing one lane to transfer such right of way to a second vehicle lane in which controller actuation has occurred and to accord a minimum period of right ofway to said second vehicle lane, 1

means acting in response to controller actuation to extend such minimum period proportional to the number of vehicles awaiting such right of way and which have actuated said controller, and means forming a part of said system to further extend such minimum right of way period in the event of the operation of said vehicle actuated control by further vehicles traversing said latter vehicle lane, after right of way has been accorded to the said latter lane.

3. A trafric control system including, in combination, a signalling means for according and interrupting right of way to traflic moving over intersecting lanes, a timer connected to and controlling the operation of said signalling means, a tramc actuatable controller for one lane and connected to said timer to cause said signalling meansto accord, responsive to controller actuation, right of way to such lane, means forming a part of said timer for maintaining the right of way accorded to either lane by said signalling meansfor at least minimum periods, and means functioning responsive to controller actuation and while right of way is interrupted with respect to the lane of the controller to automatically extend, when accorded, the minimum period of right of way to such latter lane.

4. A traffic control system including, in combination, a signalling means for according and interrupting right of way to tramc moving over intersecting lanes, a timer connected to and controlling the operation of said signalling means, a

' traflic actuatable controller for one lane and conmeans for at least a minimum period, further means forming a part of said timer whereby a period of right of way preliminary to said minimum right of way period may be accorded the operation of such iurther timer means being de pendent upon the functioning of the traffic actuated controller a plurality of times prior to the transfer of right of way to the lane of said com troller.

5. A tramc control system for a plurality of highways comprising stop and go signals therefor, means for energizing said signals to normally provide a cyclic display thereof in a predetermined periodic sequence, vehicle-responsive means for each of said highways, and means operated by said vehicle-responsive means to an extent dependent on the number of actuations thereof during that part of the periodic sequence when a stop signal is displayed on one highway to govern the energizing means to vary the period of display of the subsequent go signal for said one highway.

6. A trafiic control system for a plurality of highways comprising stop and go signals there for, means for energizing said signals to normallyprovide a cyclic display thereof in a predetermined periodic sequence, vehicle-responsive means for each of said highways, and means operated by said vehicle-responsive means to an extent dependent on the number of actuations thereof during that part of the periodic sequence when a stop signal is displayed on one highway to govern the energizing means to vary the period of display of the subsequent go signal for said one highway, the period of display 01' said subsequent go signal increasing as the number of actuations increases.

7. A trailic control system for a plurality of highways comprising stop and go signals therefor, means for energizing said signals to normally provide a cyclic display thereof in a predetermined periodic sequence, vehicle-responsive means for each of said highways, and means operated by said vehicle-responsive means upon actuation thereof during that part of the pe riodic sequence when a stop. signal is displayed to one highway and also during the signal period preceding the display of the stop signal of said one highway to govern said energizing means to vary the period of display of the subsequent go signal for said highway in accordance with the number of actuations of said vehicle responsive means.

8. A traflic control system for a plurality of highways comprising stop and go signals therefor, means for energizing said signals to normally provide a cyclic display thereof in a predetermined periodic sequence, vehicle-responsive means for each of said highways, and means operated by said vehicle-responsive means during the period of a predetermined display of signals for said highways to govern said energizing means to vary the period of the next subsequent display of signals for said highways in accordance with the number of actuations of said vehicle-responsive means.

9. A trailic control system for a plurality of interfering trafllc lanes comprising signalling means adapted to accord and interrupt right of way in such lanes, tramc responsive means in one of said lanes, a timer connected to the signalling means and trafi'lc responsive means and operable in response to actuation of said traflic responsive means when the right of way is interrupted in said one lane to cause the signalling means to accord right of way to said one lane for a time period before right of way can again be interrupted, and means forming a part of said timer to vary said right of way time period in accordance with the number of actuations of said trafiic responsive means occurring while right of way is interrupted prior to such accord of right of way.

10. A tramc control system for a plurality of interfering traffic lanes comprising signalling means adapted to accord and interrupt right of way in such lanes, traflic responsive means in one of said lanes, a timer connected to the signalling means and traffic responsive means and operable in response to actur tion of said traflic responsive means when the right of way is interrupted in said one lane to cause the signalling means to accord right of way to said one lane for a time period before right of way can again be interrupted, and means forming a part of said timer to vary said right of way time period in accordance with the number of actuations of said traffic responsive means occurring while right of way is interrupted prior to such accord of right of way, the right of way time period increasing as the number of such actuations increases.

11. A traffic control system for a plurality of interfering traffic lanes including in combination stop and go signals for the respective lanes, cyclic operating means for said signals adapted to display the same to signal "Go" successively to the several lanes and Stop" to the lanes interfering with the lane having the go signal, traflic responsive means in at least one lane, timing mechanism to determine the time of display of the go signal to the respective lanes by said operating means, said timing mechanism includcrease of the time period'of said timing device:

ing a time delay device having an adjustable time period for predetermining at least a part of the time-6'1: display of the g0 signal to said one lane, means connected with the cyclic operating;

means for connecting said traiiic responsive means to said time delay device during the display of the stop signal to said one lane to adjust said device progressively for an increased time period responsive to a series of traflic actuations and a holding device connected with said cyclic operating means to hold said time delay device so adjusted to time the next go signal display for said one lane and then reset said time delay device.

12. A trailic control system for a plurality of interfering traiiic lanes including in combination stop and go signals for the respective lanes, cyclic operating means for such signals adapted to display the same to signal "Gof successively to the several lanes and Stop to the lanes interfering with-the lanes having the go signal, an electric timing device for predetermining at least a part of the time of go signal display to one lane by said cyclic operating means, circuit means for operating said timing device including an impedance for determining the timing pe-" riod of said device, step-by-step adjusting means for said impedance and having an initial position from which it is adapted to be operated to increase said timing period by varying said impedance in steps, electromagnetic means for operating said step-by-step means one step at a time from the initial position to so increase said time period, traflic actuated means in said one lane, means operated by said cyclic operating means to connect said traflic actuated means to said electromagnetic means to so operate the latter during display of a stop signal to said one lane for increase of said time period in successive steps by successive trafiic actuations, and locking means connected with said cyclic operaing means and with said adjusting means for maintaining such time period adjustment as so increased into the next go signal display for said one lane to determine the time of display of the latter and restore said adjusting means to said initial position.

13. A trafiic control system for a plurality of interfering traiiic lanes including in combination stop and go signals for the respective lanes,

cyclic operating means for said signals adapted to display the same to signal successively to the several lanes and Stop to the lanes in-' terfering with the lane having the Go" signal, an electric timing device for predetermining at least a part of the time of go signal display to one lane by said cyclic operating means, circuit means for operating said timing device including an impedance for determining the timing period of said device, means including a ratchet for adjusting the amount of said impedance in said circuit means, the last named adjusting means having an initial position from which it is adapted to be advanced in steps to adjust said impedance to increase said timing period,

electromagnetic means for advancing said ratchet step-by-step from said iintial position to so increase said time period, other electromagnetid means for holding when operated said in successive steps by successive traflic actuations,

and further means operated by said cylclic operating means to operate said other electromagnetic means to hold said ratchet; so advanced until and during'the next followinggo signal display for said one lane and ther 'release it to restore it to its initial position.

14. A traflic control system for interfering traflic lanes including in combination signalling means, traflic actuated means in one lane, a timer connected to said signalling means and said trafdc actuated means to cause said signalling means in response to operation of said traflic actuated means to accord right of way to said one lane while interrupting right of way to the other lanes, means forming a part of said timer to maintain right of way so accorded for at least a minimum period of time before transfer of right of way from such lane can be eflected, saidmeans including a condenser, means for varying the charge on said condenser over a period of time andmeans operable upon said condenser reaching a predetermined charge to terminate said period and means operable by actuatisn of said trafllc actuated means prior to according of right of way to said one lane to vary the rate of change of charge on said condenser during said right of way minimum period.

15. A trafllc control system for the intersection of a plurality of interfering traiiic lanes, comprising trailic signals for controlling tramc at the intersection, a source of power therefor, switch means in the circuit of said signals and said source for controlling the energlzation of said signals, mechanism including an electric timer for operating said switch means, an energizing circuit for said timer having a resistance for controlling the time cycle thereof, trafllc responsive means for one of said lanes operably connected to said mechanism, means associated with said mechanism and operated by actuation of said tramc responsive means for increasing said resistance to increase the time period of energization of one of said signals.

16. A traflic control system for the intersection of a plurality of interfering trafilc lanes comprising trailic signals for controlling traflic at the intersection, a source of power therefor, switch means in the circuit of said signals and said source for controlling the energization of said signals, mechanism including an electric timer for operating said switch means, an energizing circuit for said timer having a resistance for controlling the time cycle thereof, traflic responsive means for one of said lanes operably of the length of the time cycle increasing as thenumber of actuations increases.

17. A trafiic control system for the intersection of a plurality of interfering traflic lanes comprising traflic signals for controlling traffic at the intersection, a source of power therefor, switch means in the circuit of said signals and said source for controlling the energization of said signals, mechanism including an electric timer for operating said switch means, an energizing circuit for said timer having a resistance for controlling the time cycle thereof, traflic responsive means for one of said lanes operably conne'eted to said mechanism, step-by-step adlusting means connected with said resistance and having an initial position and a plurality of additional positions to vary said resistance to vary said time cycle progressively, an electromagnetic device for advancing said step-by-step means and operably connected to said trafflc responsive means to advance said step-by-step means from its initial position through a plurality of positions to so vary said resistance progressively responsive to a plurality of actuations of said trafiic responsive means, and an electromagnetic holding device for said step-by-step means operably connected with said mechanism to hold said step-by-step means so advanced during a part of the time cycle and to reset said step-by-step means to its initial position in another part of the time cycle.

18. A traffic control system including in combination, signalling means to be disposed adjacent the point of intersection of traffic lanes, a timer for operating said signalling means to accord and interrupt right of way over said lanes, a traflic actuated control disposed in advance of said intersection and connected to said timer to govern the operation thereof, timing means forming a part of said timer and acting in response to a functioning of said traffic actuated control to accord, through said signalling means, right of way to one traflic lane for a minimum period of time, resetting means for said timing means and acting in response to a functioning of said traiilc control during such right of way period to cause said timing means to supplement said right of way period by a further time interval inversely proportionate to the speed of the traffic which actuated said control, and means functioning in the absence of right of way indication in one lane and in response to the functioning of the traffic actuated control of such lane to delay initiation of operation of said timing means for a period proportionate to the number of actuations of said control which have occurred during such absence of right of way.

19. A trafiic control system for interfering 'trafiic lanes and including, in combination, signalling means, traffic-actuated controllers to be disposed in the lanes, a timer connected to said signalling means and controllers to cause said signalling means to accord right of way to the lane in which controller actuation has occurred, while interrupting right of way to the other lane, means forming a part of said timer to cause such right of way indication to prevail for a minimum period of time and means forming a part of said timer to accord through said signalling means a right of way period preliminary to said minimum period whereby to permit vehicles awaiting such right of way to get into motion after the right of way is accorded to the lane in which controller actuation occurred.

20. A trafiic control system for interfering traflic lanes including, in combination, signalling means and a control for operating said signalling means to accord and interrupt by the latter right of way over said lanes, traffic actuated devices in said lanes, said devices being connected to said control to cause a functioning of the latter, a unit forming a part of said control to extend to a vehicle operating the device of the lane to which right of way is accorded, a prolongation of said right of way to negotiate the intersection, and means functioning in response to an operation of the traffic actuated device of one lane and in advance of the accorda tion of right of way to such lane to delay initiation of the units operation.

21. A traffic control system for interfering traffic lanes including, in combination, signalling means and a control for operating said signalling means to accord and interrupt by the latter right of way over said lanes, trafllc actuated devices in said lanes, said devices being connected to said control to cause a functioning of the latter, a unit forming a part of said control to extend to a vehicle operating the device of the lane to which right of way is accorded, a prolongation of said right of way to negotiate the intersection, means functioning in response to an operation of the tramc actuated device of one lane and in advance of the accordation of right of way to such lane to delay initiation of the unit's operation, and manually controlled means for varying the time value of such delay.

22. A trafflc control system for the intersection of traffic lanes including in combination signalling means for according and interrupting right of way in said lanes, a timer connected to said signalling means to control the same, traffic actuated means in one of said lanes and connected to said timer, said timer including timing means responsive to operation of said trafllc actuated means by traflic arriving at the intersection in one lane while right of way is interrupted therein to accord right of way thereafter to said" one lane for an initial predetermined minimum period to permit such traffic to start, further timing means for maintaining said right of way for a further minimum period immediately following said initial period to permit traflic to enter or clear the intersection, and means operable by actuation of said trafllc actuated means by further traflic arriving at the intersection during only said further minimum period to prolong accord of right of way beyond said further minimum.

23. A traffic control system for interfering traflfic lanes including in combination signalling means for according and interrupting right of way in said lanes, a timer connected to said signalling means to control the same, trafllc actuated means in one of said lanes and connected to said timer, said timer including means responsive to operation of said traflic actuated means when right of way is interrupted in said one lane to accord right of way to said one lane for at least a predetermined minimum period, two timing means for providing said minimum right of way period each timing means being adjustably presettable as to time interval, one timing means being resettable to prolong the time required for it to complete its time interval and thus to prolong right of way beyond said minimum by operation of said trafllc actuated means and the other timing means being non-resettable, said non-resettable timing means timing one part of said minimum period and said resettable timing means being operable to time the other part of said minimum period upon completion of the time interval of the non-resettable timing means.

24. A traffic control system including, in combination, a signalling means arranged adjacent the point of intersection of vehicle lanes to indicate right of way and caution to traffic traversing said lanes, a timer controlling the operation of said signalling means and operating the latter to include a caution indication for a predetermined interval preliminary to transfer of right of wayfrom one vehicle lane to the other, con

trols adapted to be actuated by vehicles in said lanes for governing the functionings of said timer, means forming a part of said system to automatically diminish the interval of caution indication preliminary to transfer of right of way by said signalling means to one vehicle lane and in the absence of controller actuation in the other vehicle lane, and means forming a part of said system and prolonging to a maximum extent the interval of caution indication preliminary to transfer of right of way from one vehicle lane to another by said signalling means and in the case of actuation of the controllers of both lanes.

25. A traffic control system for interfering trafllc lanes including signalling means, traflicactuated devices in the lanes, a timer connected to said signalling means and said traffic actuated devices whereby in response to a functioning of the device in one lane to transfer through said signalling means right of way to that lane, while interrupting right of way to the other lane,

means whereby said signalling means in transby said signalling means and in the absence of operation of the traflic actuated device in the vehicle lane which is losing right of way.

26. A traflic control system for interfering traffic lanes including signalling means, traflicactuated devices in the lanes, a timer connected to said signalling means and said traflic actuated devices whereby in response to a functioning of the device in one lane to transfer through said signalling means right of way to that lane, while interrupting right of way to the other lane, means whereby said signalling means in transferring right of way from one lane tothe other will provide a caution indication .preliminary to such transfer and for a certain interval, and means forming a part of said timer to automatically prolong to a maximum extent the interval of caution indication preliminary to transfer of right of way and in the presence of trafflc in both of said vehicle lanes as indicated by actuations of said vehicle-actuated devices.

27. A traffic control system including, in combination, a signalling means to be arranged ad- Jacent the intersection of a plurality of traflic lanes, means forming a part of said signalling means and providing cautionary, right of way, and interruption to right of way signal indications to traflic approaching the intersection over such lanes, a timer connected to and controlling the operation of said signalling means, a traffic actuatable controller for one lane and connected to said timer to cause said signalling means to accord, responsive to controller actuation, right of way to such lane, means forming a part of said timer for maintaining the right of way so accorded for a period of time, further means form-F ing a part of said timer for transferring the right of way accorded by said signalling means away from such lane after the expiration of such period of time, and additional means forming a part of said timer to cause a period of display of such cautionary indication by the signal upon such transfer and dependent upon controller actuation during the period of display of the cautionary indication by said signalling means to vary such period.

28. A traffic control system including, in combination, a signalling means to be arranged adjacent the intersection of a plurality of traflic lanes, means forming a part of said signalling means and providing cautionary, right of way, and interruption to right'of way signal indications to traflic approaching-the intersection over such lanes, a timer connected to and controlling the operation of said signalling means, a traflic actuatable controller for one lane and connected to said timer to cause said signalling means to accord, responsive to controller actuation, right of way to such lane, 'means forming a part of said timer for maintaining the right of way so accorded for at least a minimum period, further means forming a part of said timer and functioning responsive to controller actuation during such minimum period to extend the right of way indication of said signalling means beyond such period and by subsequent actuation to further extend such period, still further means forming a part of said timer for causing a transfer of right of way away from the lane of such controller upon the expiration of such extended period, and additional means forming a part of said timer for causing a period of display of said cautionary indication upon such transfer, such additional means being connected to said traflic actuated controller to cause the cautionary period to be varied by operation of said controller during such period.

29. A traffic control system for a traffic lane including signalling means for displaying right of way, denial of right of way and cautionary indications to such lane, trams actuated means for such lane, signal controlling means to dis play right of way indication to such lane in response to operation of said traflic actuated means, means operating to interrupt such display and including timing means for providing a period of cautionary indication upon such interruption and means for varying such cautionary period responsive to actuation of said traifice actuated means during said cautionary period.

30. A traflic control system for 8. H lane including signalling means for displaying right of way, denial of right of way and cautionary indications to such lane, traflic actuated means for such lane, signal controlling means to display right of way indication to such lane in response to operation of said traflic actuated means, means operable to interrupt such display and including timing means for providing a period of cautionary indication upon such interruption, said timing means including a condenser, means for varying the charge on said condenser over a period of time, and means responsive to said. condenser reaching a predetermined state of charge to terminate'said period and means connected to said charge varying means for varying the rate of change of charge responsive to operation of said trams actuated means during or immediately before the period of cautionary indication.

J OHN L. BIACH.

Y A. i 

